The 16th Royal Brigade was stationed on Kesai IV when the invasion of the Alliance began, and was deployed forward to pacify the population of Niles in 2581,[2] before taking part in the attack on Sevon in late 2581. The 16th and the other brigades of the 6th Royal Division were mauled by the Pitcairn Legion and the Alliance 4th Armored Division before the 6th Royal had managed to finish unloading from their DropShips; ColonelElias Pitcairn duped the commander of the Outworlds Alliance Task Force into an ambush, one that checked the SLDF advance and allowed the combined Alliance forces to attack the 6th Royal Division landing zone. The resulting day-long battle allowed the Alliance forces to inflict heavy damage on the 6th Royal and capture signficant quantities of salvage, and the Alliance forces would turn the fight for Sevon into a month-long campaign.[3]

Having been bloodied on Sevon, the 16th Royal Brigade wouldn't take part in another planetary invasion during UNION HOLD; the 16th Royal Brigade remained on Sevon in 2582, and spent 2583 on Tancredi IV and Haynesville, before being transferred to the war against the Taurian Concordat in 2584 along with the rest of the 6th Royal Division.[1]